It is a well known form of electronics packaging to mount circuit card assemblies (CCA's) within an electronic enclosure. The CCA's are either secured by their edges, their corners or a combination of both. These electronic assemblies are included on many vehicles such as airplanes, missiles, spacecraft or any other vehicle which develops vibrational and/or shock forces. The effects of shock and vibration are manifested in several detrimental ways. For example, the cards themselves are constructed of a dielectric material which is somewhat brittle and subject to cracks if permitted to vibrate. These cracks may extend across conductive circuit patterns and cause intermittent or total interruption of the conduction paths. Vibration can also weaken or interrupt component solder joints and cause loosening, interruption or loss of component, as well as change electrical/electronic characteristics.
One way to reduce vibrationally induced damage to each CCA is to mount each CCA such that the natural frequency, .function..sub.n, of the card is increased. Raising the .function..sub.n, decreases the deflection of the CCA during vibration, thereby reducing its stress. However, devices which have been created for this purpose have the effect of reducing the area available for mounting electronic components or adding proportionally more weight and increasing the size of the assemblies. It is important that any stiffening scheme not significantly reduce the CCA's size thereby increasing the number of CCA's required along with the number of inner connections and connectors. Further, the addition of more CCA's would result in an increase in the size of the mother board, an increase in size and weight of the total assembly, and a decrease in the reliability of the overall system.
Therefore it is the object of this invention to provide a stiffening device which is light weight, cost effective and does not significantly reduce the CCA usable area.